MacOS: Suppress deprecation warnings related to NSUserNotification

All NSUserNotification related classes have been deprecated in MacOS 11,
and this class will have to be revamped to use the new User
Notifications framework. We are suppressing the warnings for the time
being.

modules/juce_gui_extra/native/juce_PushNotifications_mac.cpp

@@ -35,6 +35,8 @@
 namespace juce
 {
 
+JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Wdeprecated-declarations")
+
 namespace PushNotificationsDelegateDetailsOsx
 {
     using Action = PushNotifications::Notification::Action;
@@ -532,4 +534,6 @@ struct PushNotifications::Pimpl : private PushNotificationsDelegate
     PushNotifications::Settings settings;
 };
 
+JUCE_END_IGNORE_WARNINGS_GCC_LIKE
+
 } // namespace juce